1. Field Of the Invention
This invention relates to an absorption cooling and heating system including an absorption heat pump refrigerating apparatus using air as a heat source having heat pipe means incorporated therein.
2. Description of the Prior Art
In absorption type refrigerating apparatus utilizing thermal energy as a source of energy, a gas fired absorption type cooling and heating system has come to attract attention. Also, an apparatus is known which uses air cooled heat exchangers using air (atmospheric air) as a heat source of the heat exchangers.
There are several combinations of a refrigerant and an absorbant available for use in absorption type refrigerating apparatus, and most common combinations used for practical purposes include water - lithium bromide, ammonia - water, and CHClF.sub.2 fluoro carbon (freon) - CH.sub.3 O(CH.sub.2 CH.sub.2 O).sub.4 CH.sub.3 or tetraethyleneglycol dimethlether.
The aforesaid gas fired absorption cooling and heating system comprises as the basic equipment of a refrigerating apparatus a generator, a condenser, expansion valves, an evaporator, an absorber and a solution pump and uses a refrigerant gas of high temperature heated and separated at the generator as a source of heat for heating and defrosting and a latent heat generated at the evaporator as a heat source for cooling.
The inventions have been developed prior to the present invention include U.S. Pat. No. 3,638,452, U.S. Pat. No. 4,207,751 and Japanese Patent Application Laid-Open No. 53052/78, for example. These documents of the prior art will be discussed.
In U.S. Pat. No. 3,527,061, the system is switched between a cooling mode and a heating mode by switching between a cold water circuit and a hot water circuit without effecting on-off control of a refrigerant circuit. A refrigerant of high temperature separated at the generator is condensed into a refrigerant in a liquid state at the condenser which is expanded to have its pressure reduced at a thermostatic expansion valve before being fed into the evaporator to cool water flowing therethrough. In a cooling mode, the water thus cooled is fed into a heat exchanger inside a space to be cooled through a water channel on-off valve so that heat exchange will take place between the cooled water and indoor air forcedly blown against the heat exchanger by a blower to thereby cool the indoor air. In a heating mode, hot water flowing through the condenser and the absorber is fed through the water channel on-off valve into the heat exchanger located in the space to be heated, to heat the indoor air by the hot water. In the heating mode, frost formed on the outdoor heat exchanger due to prolonged operation is removed by temporarily switching the water channel to suit the cooling operation.
In U.S. Pat. No. 3,638,452, on-off control of the refrigerant circuit and the water channel is not effected and the apparatus is operated only to perform a cooling operation by using cold water. A refrigerant of high temperature separated at the generator is condensed at the condenser into a refrigerant in a liquid state which is expanded and has its pressure reduced by the expansion valve before being fed into the evaporator to cool water therein for use as a cooling heat source.
In U.S. Pat. No. 4,207,751, on-off control of the refrigerant circuit is not effected and a refrigerant is fed, in a cooling mode, directly into a heat exchanger installed on a duct communicating with a space to be cooled, so as to directly cool the air. In a heating mode, heat is recovered from the condenser and absorber through a hot water circuit, so that the heat can serve as a heating heat source.
Japanese Patent Application Laid-Open No. 53052/78 discloses a heat pump type cooling and heating system using a water heat source in which cold water and hot water are obtained by effecting on-off control of the refrigerant circuit to perform cooling and heating operations. To perform a cooling operation, water cooled at the evaporator is used as a cooling heat source; to perform a heating operation, the evaporator is made to function as an absorber and the absorber is made to function as an evaporator by partly controlling the refrigerant circuit.
From the foregoing description, it will be appreciated that cooling and heating systems of the prior art using a conventional absorption type refrigerating apparatus include a system which obtains cold water and hot water serving as cooling and heating heat sources without effecting on-off control of the refrigerant circuit, a system which performs a cooling operation as a direct expansion system in which heat exchange takes place between a refrigerant and air through a heat exchanger and a heating operation by using as a heating heat source hot water obtained by utilizing both heat of absorption and heat of condensation, and a system which effects on-off control of the refrigerant circuit to obtain cold water and hot water for use as cooling and heating heat sources.
Generally, the use of an air-cooled type heat exchanger makes it necessary to effect defrosting to remove frost formed during heating operations. To effect defrosting, cooling and heating systems may be temporarily switched from the heating operation to a cooling operation, as is the case with the system described in U.S. Pat. No. 3,527,061 referred to hereinabove. However, this process has a disadvantage in that cold water is fed into the indoor heat exchanger during defrosting operation and the indoor air is cooled so that cold air is blown into the space and causes discomfor to those who are in the space. To mitigate this unpleasantness felt by the occupants of the space by reducing the volume of cold air blown into the space, the revolutional velocity of the blower may be reduced or operation of the blower may be suspended or an auxiliary heat source, such an electric heater, may be actuated to heat the air that is blown into the space. Such process is used in air cooling type heat pump cooling and heating systems using a compressor, for example. In some other systems of the compression type, a plurality of heat exchangers are used and some of them are switched to perform defrosting while other heat exchangers still perform a heating operation. However, all the remedies taken for mitigating the discomfort suffered by the occupants of the space make the system large in size and do not suit cooling and heating systems of small capacity. Meanwhile systems of the water heat source and water cooled type are not favored because restrictions on utilization of water resources are becoming stricter nowadays and apparatus utilizing water tend to be frowned upon.
Under these circumstances, creation of an absorption type cooling and heating system of the air heat source and air cooled type that is capable of conserving energy has been in demand.